Introduction: Data sharing accelerates research activities and production of science. It has numerous benefits for the stakeholders. However, researchers withhold it for different reasons. Accordingly, the present study examined the challenges refusing data sharing among Iranian researchers of medical sciences.Method: The present survey study sought to identify data sharing challenges from the medical sciences researchers’ perspectives using a questionnaire. The sample population included 400 researchers in the field of medical sciences, who had published articles in WoS databases in 2016. Descriptive and analytical statistics (independent samples t-test, one-way ANOVA and Friedman test) were used in this study.Results: Based on the mean ranks, concerns about the misuse and misinterpretation of the data (9.02), earlier publication of the shared data by others prior to their publication by the main researcher (8.71) and lack of appropriate motivational mechanisms (8.6) are the most important data sharing challenges from the viewpoints of Iranian researchers in Medical Sciences. There was a significant difference in data sharing rate between males and females (p= .003), on the one hand, and clinical and non-clinical groups of researchers in medical sciences (p= .014) on the other hand.Conclusion: The findings indicate that it is essential to familiarize the researchers with data capabilities in order to change their attitudes toward data sharing. Knowing about the benefits of sharing data facilitates the movement toward data-based research studies.